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>on the track and field teams, a diversity of skills could be found: hurdlers, sprinters, hammer throwers, javelin throwers, shot-putters, middle-distance runners, high jumpers, long jumpers, and pole vaulters. I became a distance runner. I did not have to be like anyone else, an important lesson for life.
>Distance runners have one common trait—the good ones are skinny. Weight specialists such as shot-putters or hammer throwers are a completely different sort of animal from distance runners. The two represent extremes of body build, coordination, speed, and endurance. Numerous and diverse aspects of physiology underlie those differences. The weight specialists, in order to be at the far extreme of what is humanly possible, must have a massive body of bulging muscles and thick, strong bones to support them. They require a high percentage of fast-twitch muscle fibers that anaerobically (without oxygen) burn carbohydrate for explosive release of energy. Their competitive event generally takes a second or two; the preparation, years.
>The distance runner must fairly float along the ground, sometimes for hours on end. Ideally, he has light, thin bones and long, thinly muscled limbs, like a bird. The key to the distance runner’s performance is to supply his fat-burning muscles with a sustained supply of oxygen. That capacity involves a large support system that includes a large heart capable of a large stroke volume per beat, rapid beating if need be, and slow if not. He needs large arteries, extensive development of the capillaries, large lung capacity, and large fuel depots in the muscles, the liver, and other areas of the body. His cells must be packed with mitochondria, the microscopic power units that, with their batteries of enzymes, convert the fuel and oxygen to energy, which is then harnessed for muscle contraction. The quick power of the sprinter or thrower requires no mitochondria and hence no oxygen, or the support systems for oxygen delivery.